pinchZoomThreshold property
Pinch Zoom threshold default is 0.5 Map starts to zoom when
pinchZoomThreshold has been achieved or another multi finger gesture
wins which allows MultiFingerGesture.pinchZoom Note: if
interactiveFlags
doesn't contain InteractiveFlag.pinchZoom or
enableMultiFingerGestureRace is false then zoom cannot win
Implementation
final double pinchZoomThreshold;